Discharge ring supporting structure of adjustable-blade axial-flow turbine

Abstract

A discharge ring supporting structure of an adjustable-blade axial-flow turbine comprises upper and lower halves separated along a horizontal plane passing through the central axis of the discharge ring. The lower half of the discharge ring is supported by a plurality of supporting columns, each having upper and lower supporting members. The upper supporting members are detachably connected between the lower half of the discharge ring and the lower supporting member. When it is desired to remove the runner, the discharge ring is separated into the upper and lower halves, and the upper supporting members of the supporting columns are removed so that the discharge ring can be lowered. Lowering of the discharge ring allows the runner to be lowered and then removed axially without the runner blades contacting the discharge ring. The upper supporting members of the discharge ring supporting columns are provided with a vibration damper for damping vibration in the discharge ring.

What is claimed is: 
     
       1. In a discharge ring supporting structure of an adjustable-blade axial-flow turbine having a bulb containing a generator and a main shaft therein and disposed along a water flow, a runner mounted on an end of said bulb on the downstream side and having a plurality of blades, and a discharge ring surrounding said blades of said runner so as to form a throat portion, the diameter of which is smaller than the maximum diameter of a circle formed by the rotation of said blades around the axis thereof, said discharge ring supporting structure being connected to said discharge ring and a fixed floor, characterized in that said discharge ring supporting structure comprises a plurality of supporting members vertically integrated, and at least one of said supporting members being detachably mounted to the lower half of said discharge ring which is divided by a horizontal plane into upper and lower halves, and to the other supporting member, whereby the height of said discharge ring supporting structure is adjustable. 
     
     
       2. The discharge ring supporting structure as defined in claim 1, wherein said plurality of supporting members each comprise upper and lower supporting members, the height of said upper supporting member being larger than the minimum distance by which said lower half discharge ring is lowered to enable said runner to move axially and freely from contact between said discharge ring and said runner blades. 
     
     
       3. The discharge ring supporting structure as defined in claim 2, wherein said discharge ring comprises a plurality of upper and lower supporting members, at least two said upper and lower supporting members being arranged on the same periphery of said lower half discharge ring, and at least one said upper and lower supporting member being arranged on said lower half discharge ring at a position different from said periphery on which said two upper and lower supporting members are arranged. 
     
     
       4. The discharge ring supporting structure as defined in claim 2, wherein one of said upper and lower supporting members is smaller in rigidity than the other and includes therein a vibration damper. 
     
     
       5. The discharge ring supporting structure as defined in claim 2, wherein at least one of said upper and lower supporting members cylindrical and contains therein an oil damper for damping vibration caused in said discharge ring. 
     
     
       6. The discharge ring supporting structure as defined in claim 5, wherein said upper supporting member is cylindrical, and said oil damper comprises a cylinder secured to said lower supporting member, a piston disposed in said cylinder and dividing the interior of said cylinder into two oil chambers, a rod connected to said piston and said lower half discharge ring, a passage communicating between said two oil chambers, and an adjustable screw provided in said passage for adjusting flow of oil from one of said oil chambers to the other of said chambers. 
     
     
       7. An adjustable blade axial-flow turbine with a discharge ring supporting structure for supporting the discharge ring above a fixed floor, comprising: a bulb containing a generator and a main shaft therein and disposed within a water flow;   a runner mounted on an end of said bulb on the downstream side thereof and having a plurality of blades;   a discharge ring surrounding said blades of said runner so as to form a throat portion, the diameter of which is smaller than the maximum diameter of a circle formed by the rotation of said blades around the axis thereof, said discharge ring having an upper half and a lower half separately secured to each other at a horizontal plane containing a central axis of said discharge ring; and   said discharge ring supporting structure including a plurality of supporting columns each mounted on said lower half of said discharge ring at their one end and on said fixed floor at their other end for supporting said discharge ring, each of said supporting columns comprising a plurality of column pieces vertically integrated, at least one of said column pieces being detachably integrated so that the height of said lower half of said discharge ring is adjustable and said lower half discharge ring can be lowered to enable said runner to move axially and freely from contact between said discharge ring and said runner blades.   
     
     
       8. The adjustable blade axial-flow turbine with a discharge ring supporting structure as defined in claim 7, wherein one of said plurality of supporting columns is smaller in spring constant than the other and includes therein a vibration damper for damping vibration caused in said discharge ring. 
     
     
       9. The adjustable blade axial-flow turbine with a discharge ring supporting structure as defined in claim 7, wherein a pair of said supporting columns are mounted on a first periphery of said discharge ring lower half and another pair of said supporting columns on another periphery of said discharge ring lower half, which is axially spaced from said first periphery. 
     
     
       10. An adjustable blade axial-flow turbine and discharging with a discharge ring supporting structure for supporting the discharge ring above a fixed floor, comprising: a bulb containing a generator and a main shaft therein and disposed within a water flow;   a runner mounted on an end of said bulb on the downstream side thereof and having a plurality of blades;   a discharge ring surrounding said blades of said runner forming a throat portion having a minimum diameter portion downstream of said blades, said minimum diameter being smaller than the maximum diameter of a circle formed by the rotation of said blades, said discharge ring having upper and lower half portions separately secured to one another along a horizontal plane passing through the central axis of said discharge ring; and   said discharge ring supporting structure having a plurality of supporting columns having opposite ends, one end of each of said columns being mounted to said lower half portion of said discharge ring and the other end of each of said columns being mounted to said fixed floor for supporting said discharge ring, each of said supporting columns being integrally formed from a plurality of column pieces integrally connected to one another such that at least one of said column pieces is removable for lowering the height of said lower half portion in relation to said fixed floor for enabling said runner to be lowered and moved horizontally without said runner blades contacting said throat portion of said discharge ring.